Strategic coating of NdFeB magnets with Dy to improve the coercivity of permanent magnets

Journal Article · Fri Dec 25 00:00:00 EST 2015 · Advances in Materials Research

DOI:https://doi.org/10.12989/amr.2015.4.4.227· OSTI ID:1286953

Ucar, Huseyin ^[1]; Parker, David S. ^[1]; Nlebedim, I. C. ^[2]; McCallum, R. W. ^[2]; McCall, S. K. ^[3]; Parans Paranthaman, M. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Ames Lab., Ames, IA (United States)
3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Here, we present a method, supported by theoretical analysis, for optimizing the usage of the critical rare earth element dysprosium in Nd₂Fe₁₄B (NdFeB)-based permanent magnets. In this method, we use Dy selectively in locations such as magnet edges and faces, where demagnetization factors are most significant, rather than uniformly throughout the bulk sample. A 200 nm thick Dy film was sputtered onto commercial N-38, NdFeB magnets with a thickness of 3 mm and post-annealed at temperatures from 600 - 700 C. Magnets displayed enhanced coercivities after post-annealing. Furthermore, our experimental results indicate as large as a 5 percent increase in the energy product of NdFeB magnets, achieved for a total Dy weight percentage of 0.06 percent, much less than that used in commercial grade Dy-NdFeB magnets. Finally, by assuming all Dy diffused into NdFeB magnets, the improvement in energy product corresponds to a saving of over 1% Dy (critical element). Magnets manufactured using this technique will therefore be higher performing and significantly less expensive than those made presently.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Critical Materials Institute (CMI)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (EE-5A)
• Grant/Contract Number: AC05-00OR22725; AC52-07NA27344
• OSTI ID: 1286953
• Alternate ID(s): OSTI ID: 1409963
• Report Number(s): LLNL-JRNL--688660
• Journal Information: Advances in Materials Research, Journal Name: Advances in Materials Research Journal Issue: 4 Vol. 4; ISSN 2234-0912
• Publisher: Techno-Press
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
NdFeB magnets
magnetic properties
selective Dy diffusion
sputter deposition
theoretical analysis